The future of London City Airport’s £200million expansion plans rests on a quarrel over the method for calculating noise nuisance.

While campaigners at a planning inquiry at City Hall are hoping to raise a range of deep-rooted objections – including air quality and the “festering anger” among residents – the crux of the issue is likely to be a technicality – which formula best describes who is affected by the airport’s growth.

The number of households in dispute is relatively small – about 8,800 homes on the fringes – but the impact on LCY’s costs could be significant – up to £29.5million to fit insulation measures.

The planning appeal, set to last four weeks, is unlikely to challenge the growth of aviation in the capital, which appeared to be the motive of the Mayor of London Boris Johnson when he blocked the scheme a year ago after it had been passed by Newham Council.

At that time, the decision was billed as a broadside by Boris Johnson in pursuit of his cherished dream of an island airport in the Thames estuary. LCY’s aspirations to build new terminal buildings and accommodate larger aeroplanes appeared to be collateral damage in the debate over Heathrow’s third runway.

Common ground

But much of the heat has gone out the battle since then and the lawyers gathered in City Hall surrounded by mountains of documents on Tuesday found themselves sharing common ground on many key points.

They agree the issue is not the air quality, the impact on the “Blue Ribbon” waterway network, the extra traffic or the safety zones.

The mayor’s team said he welcomed the economic benefits the upgrade would bring and Mr Johnson was not vexed by the overall marginal increase in noise levels that will arise from a possible 111,000 plane movements a year, up from a “fallback” figure of 95,000.

His objection, once distilled through the prism of planning policy, comes down to the method of measuring which houses sit on the threshold of a noise nuisance as determined by two contradictory methodologies.

Both sides consider their opponents’ formula flawed.

The method adopted by Newham, and London City Airport takes an average figure for the whole affected area and say this is in line with Government policy. The mayor’s experts say this has no relevance to City Airport.

Contour map

The difference between those affected according to 57dB according 'average' noise (green) calculations and 'single mode' measurements (pink) – 2023

Overlaid on a map, the two contours are broadly similar but there are areas when the “single mode” bulges further than the “average” contour – mostly in the Thamesmead area in the east and towards Poplar in the west – and it is these disputed zones which are the frontline in this appeal.

Douglas Edwards, QC for the Greater London Authority said: “London City Airport has one runway which operates in one of two modes – westerly, 70% of the time the airport is operational, or easterly, 30% of the time. There is no third mode for London City Airport called ‘average’.

“If the appeal is allowed, a substantial number of residents will be exposed to a level of noise, which is agreed represents the onset of community annoyance for 70% of the time; a different group of residents will similarly be exposed for 30% of the time.

“On London City Airport’s approach, these residents would be denied any mitigation through the offer of noise insulation.”

Counsel for the airport Michael Humphries says this algorithm “lacks technical justification” and, if allowed, would signal a significant change in national policy.

Campaigners' plea

Campaign group Hacan East is represented at the inquiry. John Stewart told planning inspector Martin Whitehead: “While we try to engage with the modelling and the stats and the technical details – sometimes more successfully than others – our position is informed by something quite simple; our supporter base believes that current noise levels are unacceptable.

“Our supporters have felt over the years that their voices have not been heard, not by the airport, not by Newham. Many residents close to the airport have felt abandoned.

“They have felt overwhelmed by this planning application which has lasted over two and a half years.

“Consultation after consultation have blindsided and jaded local people who do not know what is going on, and have given up trying to understand it.”